Search results

Formations of ultrafine grains are preferred over coarse grain structures.
Mechanism of grain refinement involves continuous generation and multiplication of dislocation in the coarse grains during deformation and their subsequent rearrangement through migration leads to formation of sub-grains with dense dislocation walls.
In this process, Nano-structured grain size can be achieved [13-16].
The increase in microhardness values is due to the grain refinement.
Uniform microhardness distribution increases with number of passes.

OpenMP employs shared variable model and is particularly applicable to fine-grained parallel computing.
It is thus able to obtain the fine-grained parallel decomposition algorithm.
The number of threads is usually the same with the number of cores in the processor.
When the number of threads is determined, column computation can be separated into blocks in terms of the number of threads.
· The parallel decomposition method presented by this paper belongs to fine-grained parallel computation.

That is, as the average alumina grain size of the composites decreased, the number of bendings per CNF increased, which resulted in an enhancement of the fracture toughness of the composites [5].
Each alumina grain was confirmed by the channeling contrast of BSE.
Only a few dark areas were observed inside of alumina grains, which indicates that most of the CNTs distributed at alumina grain boundaries.
Average alumina grain sizes and alumina grain size distributions of the CNTs and CNFs/alumina composites are shown in Fig. 4 and 5, respectively.
The other side, the AT- CNTs having a larger amount of defect could controll the grain boundary migrations, which resulted in smaller average alumina grain sizes and narrower alumina grain size distributions [4].

The nanostructure material means: the atoms in these materials are arranged in nano-sized clusters, which build up the grains, and these grains contain only about 900 atoms, with a grain length scale less than 100 nm
[1] As the grain size decreasing the volume fraction of grain boundaries is increasing and this parameter strongly affects the mechanical properties of the material.
Compression test The true stress-true strain curves are running higher for higher number of ECAP passes, just in case of the second pass it is running lower.
The maximum forces are increasing with increasing number of ECAP passes just for the second pass it is slightly smaller (Fig. 12).
[6] Creep and microstructural characteristics of an ultrafine grained aluminum processed by equal channel angular pressing (ECAP)

Multi-ingredient system of mixing grain materials is a system where the number of permanent ingredients amounts to at least 3.
Simultaneous mixing of the k number of ingredients (k>2) causes a completely new quality problems [2, 3].
Even the morphology of the grains surface can have an impact on the run of the mixing process [4, 5].
It is a grain composition made of 13 ingredients.
The concentration of all the ingredients was evaluated for all components of the mixture in bags with the following numbers: 4, 12, 20, 28, 36, 44, 52, 60, 68, 76 and 80.

This reduction in grain size leads both to a very high strength at ambient temperatures and to a potential for achieving a superplastic forming capability at elevated temperatures.
Inspection of Fig. 2 shows several important trends describing the hardness evolution through the disk thickness with increasing numbers of revolutions.
Fourth, the tolerance of the error bars decreases with increasing numbers of turns.
Inspection of Fig. 3 also leads to several conclusions for the evolution in hardness homogeneity wth increasing numbers of HPT turns.
However, for a material such as the Zn-22% Al eutectoid alloy, the hardness values are lower rather than higher after HPT even though the grain size is reduced by processing [12,13].

Narbutta 85, 02-524 Warsaw, Poland aa.rosochowski@strath.ac.uk, bl.olejnik@wip.pw.edu.pl Keywords: severe plastic deformation, incremental forming, equal channel angular pressing, ultrafine grained metals.
Introduction Bulk metals with ultrafine grained (UFG) structure, characterised by the average grain size <1 mm, draw substantial attention due to their unique mechanical and physical properties.
In this method, a very large plastic deformation (true strain >3, depending on the metal) "subdivides" coarse metal grains into sub-micrometre size grains.
There have been a number of publications describing further developments of the method and experimental results, e.g. [7].
Force, kN Acknowledgements Part of this research was supported by the Engineering and Physical Sciences Research Council [grant number EP/G03477X/1].

Introduction In cloth molding design, in order to achieve the desired tiered effect, the designer always likes taking straight and inclined grains at 45 degrees angle as the center line of garment pieces.
Lay the patterns on the 45 pieces of fabrics above-mentioned, align the side seam of a side of skirt pieces with the radial straight thread of fabric, after cutting along the pattern, 45 pieces of skirt samples can be obtained and the center line of skirt pieces just is the straight and inclined grain.
Fig. 1 Skirt Piece Sample Drawing Fig. 2 Picture of Skirt Hem Data Acquisition for Skirt Hem Parameters.The skirt hem differs in shape and size with the different draping property. 【3】 in the shot 45 pictures of skirt hem, respectively obtain hem area, tiered peak number, tiered peak length a, tiered peak length b, the angle between adjacent peaks x5, angle between adjacent tiered valley x6 and the standard deviation of these parameters.
(2) Tiered peak length x3 and tiered valley length x4 resulted from the measured data a and b respectively multiplied by 4.33; tiered number, angel between adjacent tiered peak and angle between tiered valley are subject to the measured data; the standard deviation of tiered peak length, tiered valley length, angle between adjacent tiered peaks and angle between tiered valleys are calculated by STDEV function of EXCLE software.
Table 2 Variables Introduction or Elimination Fit process step number of regression model Independent variable introduced for regression equation Independent variable eliminated from regression equation Criterion of independent variable introduced for or eliminated from regression equation 1 x1 .

All the homogenized billets consist of nearly equiaxed a-Mg grains with second-phase particles.
In addition, a number of fine dynamic precipitates are formed in all the extruded alloys (Fig. 4(d)–(f)), which also correspond to the Mg2Sn phase.
These Mg2Sn precipitates are known to effectively refine the grains of extruded Mg alloys by suppressing the growth of DRXed grains through the grain-boundary pinning effect [8,9,12,13].
This is because a smaller grain size and more abundant Mg2Sn precipitates in the TAZ1111 alloy result in an enhancement of the grain-boundary and precipitate hardening effects during tensile deformation.
In addition, the TAZ1111 alloy shows a smaller grain size owing to the enhanced grain-boundary pinning effect induced by numerous precipitates.

It can be seen that the surface of the NiO thin film annealed at 100℃ is very smooth meaning the grain size is very small.
The grain size of the nickel oxide thin film annealed at 100℃ is small, and specific surface area is big because there are lots of grain boundaries in the films.
And the crystallization of the thin films turns better, because the number of the hole carriers arisen by interval oxygen become smaller.
This is proposed to be two factors below: (i) Although the number of ions inserted in the nickel oxide thin films annealed at 200℃ and 400℃ becomes larger because of the activation process, OH- inserted in the films didn’t take part in the coloration redox reaction effectively but in another redox reaction according to the following equation: 4OH- → 2H2O + O2 + 4 e - (3) (ii) The coloration redox reaction processes are believed to firstly occur at grain boundaries and on grain surfaces, so electron holes produced by the coloration redox reaction couldn’t be dispersed in the films evenly because of high crystallization of the nickel oxide films annealed at high temperature and big grain size.
The electrochemical reversibility of nickel oxide thin films turned worse as the number of the cycles increased.